Fix the dhparam download.

defaults/main.yml

@@ -1,6 +1,6 @@
 ---
 postfix_enabled: True
-postfix_install_packages: True
+postfix_install_packages: '{{ postfix_enabled }}'
 
 postfix_relay_rh_pkgs:
   - postfix

tasks/smtp-common-packages.yml

@@ -20,9 +20,7 @@
       notify: Reload postfix
 
     - name: Download a DHPARAM file from the mozilla ssl configurator site
-      get_url: url='https://ssl-config.mozilla.org/ffdhe2048.txt' dest={{ postfix_tls_dhparam_file }}
-      args:
-        creates: '{{ postfix_tls_dhparam_file }}'
+      get_url: url='https://ssl-config.mozilla.org/ffdhe2048.txt' dest={{ postfix_tls_dhparam_file }} force=no
       when: postfix_tls_encryption_level != "old"
       notify: Reload postfix